/*
 * Copyright (c) 2013-2021, Intel Corporation
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 *  * Redistributions of source code must retain the above copyright notice,
 *    this list of conditions and the following disclaimer.
 *  * Redistributions in binary form must reproduce the above copyright notice,
 *    this list of conditions and the following disclaimer in the documentation
 *    and/or other materials provided with the distribution.
 *  * Neither the name of Intel Corporation nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 */

#include "load_elf.h"

#include "intel-pt.h"

#include <stdio.h>
#include <elf.h>
#include <inttypes.h>
#include <errno.h>
#include <string.h>
#include <limits.h>


static int load_section(struct pt_image_section_cache *iscache,
			struct pt_image *image, const char *name,
			uint64_t offset, uint64_t size, uint64_t vaddr)
{
	if (!iscache)
		return pt_image_add_file(image, name, offset, size, NULL,
					 vaddr);
	else {
		int isid;

		isid = pt_iscache_add_file(iscache, name, offset, size, vaddr);
		if (isid < 0)
			return isid;

		return pt_image_add_cached(image, iscache, isid, NULL);
	}
}

static int load_elf32(struct pt_image_section_cache *iscache,
		      struct pt_image *image, FILE *file, uint64_t base,
		      const char *name, const char *prog, int verbose)
{
	Elf32_Ehdr ehdr;
	Elf32_Half pidx;
	int64_t offset;
	size_t count;
	int errcode, sections;

	errcode = fseek(file, 0, SEEK_SET);
	if (errcode) {
		fprintf(stderr,
			"%s: warning: %s error seeking ELF header: %s.\n",
			prog, name, strerror(errno));
		return -pte_bad_config;
	}

	count = fread(&ehdr, sizeof(ehdr), 1, file);
	if (count != 1) {
		fprintf(stderr,
			"%s: warning: %s error reading ELF header: %s.\n",
			prog, name, strerror(errno));
		return -pte_bad_config;
	}

	errcode = fseek(file, (long) ehdr.e_phoff, SEEK_SET);
	if (errcode) {
		fprintf(stderr,
			"%s: warning: %s error seeking program header: %s.\n",
			prog, name, strerror(errno));
		return -pte_bad_config;
	}

	/* Determine the load offset. */
	if (!base)
		offset = 0;
	else {
		uint64_t minaddr;

		minaddr = UINT64_MAX;

		for (pidx = 0; pidx < ehdr.e_phnum; ++pidx) {
			Elf32_Phdr phdr;

			count = fread(&phdr, sizeof(phdr), 1, file);
			if (count != 1) {
				fprintf(stderr,
					"%s: warning: %s error reading "
					"phdr %u: %s.\n",
					prog, name, pidx, strerror(errno));
				return -pte_bad_config;
			}

			if (phdr.p_type != PT_LOAD)
				continue;

			if (phdr.p_vaddr < minaddr)
				minaddr = phdr.p_vaddr;
		}

		offset = base - minaddr;
	}

	errcode = fseek(file, (long) ehdr.e_phoff, SEEK_SET);
	if (errcode) {
		fprintf(stderr,
			"%s: warning: %s error seeking program header: %s.\n",
			prog, name, strerror(errno));
		return -pte_bad_config;
	}

	for (sections = 0, pidx = 0; pidx < ehdr.e_phnum; ++pidx) {
		Elf32_Phdr phdr;

		count = fread(&phdr, sizeof(phdr), 1, file);
		if (count != 1) {
			fprintf(stderr,
				"%s: warning: %s error reading phdr %u: %s.\n",
				prog, name, pidx, strerror(errno));
			return -pte_bad_config;
		}

		if (phdr.p_type != PT_LOAD)
			continue;

		if (!phdr.p_filesz)
			continue;

		errcode = load_section(iscache, image, name, phdr.p_offset,
				       phdr.p_filesz, phdr.p_vaddr + offset);
		if (errcode < 0) {
			fprintf(stderr, "%s: warning: %s: failed to create "
				"section for phdr %u: %s.\n", prog, name, pidx,
				pt_errstr(pt_errcode(errcode)));
			continue;
		}

		sections += 1;

		if (verbose) {
			printf("%s: phdr %u [%s]", prog, pidx, name);
			printf(" offset=0x%" PRIx32, phdr.p_offset);
			printf(" size=0x%" PRIx32, phdr.p_filesz);
			printf(" vaddr=0x%" PRIx32, phdr.p_vaddr);
			printf(".\n");
		}
	}

	if (!sections)
		fprintf(stderr,
			"%s: warning: %s: did not find any load sections.\n",
			prog,  name);

	return 0;
}

static int load_elf64(struct pt_image_section_cache *iscache,
		      struct pt_image *image, FILE *file, uint64_t base,
		      const char *name, const char *prog, int verbose)
{
	Elf64_Ehdr ehdr;
	Elf64_Half pidx;
	int64_t offset;
	size_t count;
	int errcode, sections;

	errcode = fseek(file, 0, SEEK_SET);
	if (errcode) {
		fprintf(stderr,
			"%s: warning: %s error seeking ELF header: %s.\n",
			prog, name, strerror(errno));
		return -pte_bad_config;
	}

	count = fread(&ehdr, sizeof(ehdr), 1, file);
	if (count != 1) {
		fprintf(stderr,
			"%s: warning: %s error reading ELF header: %s.\n",
			prog, name, strerror(errno));
		return -pte_bad_config;
	}

	if (LONG_MAX < ehdr.e_phoff) {
		fprintf(stderr, "%s: warning: %s ELF header too big.\n",
			prog, name);
		return -pte_bad_config;
	}

	errcode = fseek(file, (long) ehdr.e_phoff, SEEK_SET);
	if (errcode) {
		fprintf(stderr,
			"%s: warning: %s error seeking program header: %s.\n",
			prog, name, strerror(errno));
		return -pte_bad_config;
	}

	/* Determine the load offset. */
	if (!base)
		offset = 0;
	else {
		uint64_t minaddr;

		minaddr = UINT64_MAX;

		for (pidx = 0; pidx < ehdr.e_phnum; ++pidx) {
			Elf64_Phdr phdr;

			count = fread(&phdr, sizeof(phdr), 1, file);
			if (count != 1) {
				fprintf(stderr,
					"%s: warning: %s error reading "
					"phdr %u: %s.\n",
					prog, name, pidx, strerror(errno));
				return -pte_bad_config;
			}

			if (phdr.p_type != PT_LOAD)
				continue;

			if (phdr.p_vaddr < minaddr)
				minaddr = phdr.p_vaddr;
		}

		offset = base - minaddr;
	}

	errcode = fseek(file, (long) ehdr.e_phoff, SEEK_SET);
	if (errcode) {
		fprintf(stderr,
			"%s: warning: %s error seeking program header: %s.\n",
			prog, name, strerror(errno));
		return -pte_bad_config;
	}

	for (sections = 0, pidx = 0; pidx < ehdr.e_phnum; ++pidx) {
		Elf64_Phdr phdr;

		count = fread(&phdr, sizeof(phdr), 1, file);
		if (count != 1) {
			fprintf(stderr,
				"%s: warning: %s error reading phdr %u: %s.\n",
				prog, name, pidx, strerror(errno));
			return -pte_bad_config;
		}

		if (phdr.p_type != PT_LOAD)
			continue;

		if (!phdr.p_filesz)
			continue;

		errcode = load_section(iscache, image, name, phdr.p_offset,
				       phdr.p_filesz, phdr.p_vaddr + offset);
		if (errcode < 0) {
			fprintf(stderr, "%s: warning: %s: failed to create "
				"section for phdr %u: %s.\n", prog, name, pidx,
				pt_errstr(pt_errcode(errcode)));
			continue;
		}

		sections += 1;

		if (verbose) {
			printf("%s: phdr %u [%s]", prog, pidx, name);
			printf(" offset=0x%" PRIx64, phdr.p_offset);
			printf(" size=0x%" PRIx64, phdr.p_filesz);
			printf(" vaddr=0x%" PRIx64, phdr.p_vaddr);
			printf(".\n");
		}
	}

	if (!sections)
		fprintf(stderr,
			"%s: warning: %s: did not find any load sections.\n",
			prog,  name);

	return 0;
}

int load_elf(struct pt_image_section_cache *iscache, struct pt_image *image,
	     const char *name, uint64_t base, const char *prog, int verbose)
{
	uint8_t e_ident[EI_NIDENT];
	FILE *file;
	size_t count;
	int errcode, idx;

	if (!image || !name)
		return -pte_invalid;

	file = fopen(name, "rb");
	if (!file) {
		fprintf(stderr, "%s: warning: failed to open %s: %s.\n", prog,
			name, strerror(errno));
		return -pte_bad_config;
	}

	count = fread(e_ident, sizeof(e_ident), 1, file);
	if (count != 1) {
		fprintf(stderr,
			"%s: warning: %s failed to read file header: %s.\n",
			prog, name, strerror(errno));

		errcode = -pte_bad_config;
		goto out;
	}

	for (idx = 0; idx < SELFMAG; ++idx) {
		if (e_ident[idx] != ELFMAG[idx]) {
			fprintf(stderr,
				"%s: warning: ignoring %s: not an ELF file.\n",
				prog, name);

			errcode = -pte_bad_config;
			goto out;
		}
	}

	switch (e_ident[EI_CLASS]) {
	default:
		fprintf(stderr, "%s: unsupported ELF class: %d\n",
			prog, e_ident[EI_CLASS]);
		errcode =  -pte_bad_config;
		break;

	case ELFCLASS32:
		errcode = load_elf32(iscache, image, file, base, name, prog,
				     verbose);
		break;

	case ELFCLASS64:
		errcode = load_elf64(iscache, image, file, base, name, prog,
				     verbose);
		break;
	}

out:
	fclose(file);
	return errcode;
}